In the sealing of cardboard cartons the usual procedure is to place an adhesive or glue on the adjacent surfaces of the top flaps, fold the flaps to the closed position and hold the flaps in that position until the glue sets sufficiently to retain the flaps in that position. While there have been advances made in quick-acting glues, still the flaps must be held in the closed position by an external force for a period of time sufficient to allow the glue to set and retain the flaps.
Difficulties arise in holding the flaps because they do not always fold completely flat but are frequently higher in the middle than on the sides. In addition other irregularities in the configuration of the folded flaps can exist. For instance, depending upon how full the container is, the vertical spacing between the flaps and the carton bottom can change even between containers formed from the same size blanks due to the fullness of the carton, variations in the position of the bend of the flaps, et cetera. In addition if the contents of the container are at all fragile or can be deformed by the exertion of excessive force on the top, the amount of force exerted on the container top must be limited. Thus there is the need for such apparatus to function with more than one carton size to increase the usefulness and efficiency of the equipment.
It is the primary purpose of this invention to provide a carton hold-down apparatus of improved design and construction which will accommodate different carton sizes and effectively retain the flaps closed while the glue sets without interrupting the forward progress of the carton.